1. Field of the Invention:
This invention relates generally to multiple speed transmissions for bicycles and tricycles, and more particularly to bicycle drive transmissions of the chainless type.
2. Description of the Prior Art:
A standard ten-speed bicycle uses a chain and derailleur system. The chain requires periodic cleaning and oiling for efficient operation and to prevent premature chain failure, and it must be removed from the rear sprocket to change the rear tire. Also, when the rider is bearing down on the pedals on a hill, the derailleur usually will not carry the chain to a lower gear. Consequently, with a chain derailleur/system, the cyclist must anticipate the terrain and shift gears before getting onto the hill in a gear that is too high, since he will not be able to shift to a lower gear once he is on the hill. Further, all the gears of a conventional ten-speed are not efficiently usable because of the angle the chain makes with the sprockets. In addition, shifting is not done in a simple set sequence that is easily mastered. These problems are eliminated with the present invention, as will be seen.
The transmission described in U.S. Pat. No. 2,505,464 by Debuit is located on the axis of the wheel concentric with the pedal drive shaft as is the present invention. However, Debuit's transmission carries the pedal torque through single gear teeth requiring heavy gears, is mounted alongside the wheel hub rather than inside it, is limited in the number of gear ratios it makes available (four plus a direct drive option), and uses rows of balls and internal pistons for locking the pinion gears mounted loose on a hollow axle to the axle. The arrangement does not appear to be practical because centrifugal force is continually pushing the balls outward into engagement with the pinions that are intended to slide freely on the hollow shaft.